Exosomal irisin from FNDC5-engineered BMSCs improves ischemic stroke via inhibiting YAP/EGR1/ACSL4-mediated ferroptosis

Abstract

Background

BMSCs-derived exosomes play an important role in ischemic stroke. Irisin and its precursor fibronectin type III domain-containing protein 5 (FNDC5) are implicated in neuroprotective effect. We aimed to clarify the role of exosomal irisin from FNDC5-overexpressed BMSCs in ischemic stroke.

Methods

Oxygen-glucose deprivation and reoxygenation (OGD/R) neuronal cells (HT-22 and Neuro-2a cells) model and middle cerebral artery occlusion (MCAO) mice model were established. Exosomes were isolated from FNDC5-overexpressed BMSCs (BMSCs-FNDC5-exos). Cell viability was estimated with CCK-8. Fe²⁺, lactate dehydrogenase (LDH), glutathione (GSH) and malondialdehyde (MDA) were determined with commercial kits. Moreover, lipid reactive oxygen species (ROS) was analyzed using flow cytometry. Neurological dysfunction, infarct volume and mitochondria injury were estimated with modified neurological severity score (mNSS), TTC staining and transmission electron microscopy (TEM). Chromatin immunoprecipitation and dual luciferase assay were applied to verify the molecular interactions. Western blot, RT-qPCR and ELISA were performed for the detection of related genes and proteins.

Results

YAP, EGR1 and ACSL4 were increased in OGD/R-subjected cells. Irisin from BMSCs-FNDC5-exos elevated cell viability and suppressed ferroptosis. EGR1 transcriptionally upregulated ACSL4 and promoted OGD/R-induced ferroptosis. Additionally, YAP transcriptionally upregulated EGR1 and promoted OGD/R-induced ferroptosis. EGR1 or YAP overexpression could reverse the effects of BMSCs-FNDC5-exos. EGR1 silencing or BMSCs-FNDC5-exos overturned the facilitated ferroptosis induced by YAP overexpression, meanwhile, EGR1 silencing further enhanced the effect elicited by BMSCs-FNDC5-exos. BMSCs-FNDC5-exos reduced cerebral infarction, improved neurological impairment, inhibited ferroptosis, downregulated YAP, EGR1, ACSL4 and up-regulated irisin in MCAO mice.

Conclusion

Exosomal irisin from FNDC5-overexpressed BMSCs improves ischemic stroke via inhibiting YAP/EGR1/ACSL4-mediated ferroptosis, which shed light on discovering new strategy against ischemic stroke.